Mike,
I actually have my Battery pack about in the same location, just didn't butcher up anything. I made a bracket just behind the former were the wing bolts mount to the fuse (on the deck area under the turtle deck). Have you measured your CG? I'm curious of how many inches back from the leading edge you are? Are you using many mixing functions? What engine did you go with? Mine came out a bit nose heavy, so far I have about 3/4 oz. lead in the rear.

Thanks for any input,
EdMan